Abstract : The protection of cryptographic mechanisms is an important challenge while developing a system
of information because they allow to ensure the security of processed data. Since both hardware
and software supports are used, the protection techniques have to be adapted depending on the
context.
For a software target, legal means can be used to limit the exploitation or the use. Neverthe-
less, it is in general difficult to assert the rights of the owner and prove that an unlawful act had
occurred. Another alternative consists in using technical means, such as code obfuscation, which
make the reverse engineering strategies more complex, modifying directly the parts that need to
be protected. Concerning hardware implementations, the attacks can be passive (observation of
physical properties) or active (which are destructive). It is possible to implement mathematical
or hardware countermeasures in order to reduce the information leakage during the execution of
the code, and thus protect the module against some side channel attacks.
In this thesis, we present our contributions on theses subjects. We study and present the soft-
ware and hardware implementations realised for supporting elliptic curves given in Jacobi Quar-
tic form. Then, we discuss issues linked to the generation of curves which can be used in cryp-
tography, and we propose an adaptation to the Jacobi Quartic form and its implementation. In a
second part, we address the notion of code obfuscation. We detail the techniques that we have
implemented in order to complete an existing tool, and the complexity module which has been
developed.